Social categorization and threat of ostracism as determinants of reactions to deviant behaviour: A story about bad apples and black sheep

Within a public good dilemma people have a tendency to follow the behaviour of a single non-cooperative individual (i.e., a “bad apple”) rather than the behaviour of a single cooperative individual. The present research shows that this “bad apple”-effect is stronger when the deviant individual is categorized as an ingroup member (i.e., when the “bad apple” is a “black sheep”) rather than an outgroup member. Furthermore, inconsistent with research on the “black-sheep”-effect, the deviant individual was evaluated more extreme when he or she was categorized as an ingroup member rather than an outgroup member. In addition, the present research demonstrates that the “bad apple”-effect can be attenuated when there is a threat to be ostracized. That is, consistent with a functional perspective on ostracism, the possibility to be excluded from the group reduced the tendency to follow the behaviour of a non-cooperative individual. The findings are discussed in relation to social identity theory, self-categorization theory, and work on ostracism.